Unrelenting downpours, fresh floods and landslides are hampering efforts to provide urgently needed food to millions of people displaced or stranded by floods across Pakistan, reports Christian relief group World Vision.

Although water had begun to recede in some areas following last week’s floods, new rains have closed roads and washed out bridges, making it difficult for aid workers to move around the country, the international relief and development agency added in a report Monday afternoon.

“Until the water recedes or we have access to boats or helicopters, it will be nearly impossible for our teams to access some of the worst affected areas for assessments and delivery of relief supplies,” said Shaharyar Bangash, World Vision's Program Manager in Pakistan’s Khyber Pakhtoonkhwa Province.

And delays in providing aid means that food shortages and hunger will become an even bigger problem.

“We are very concerned about the people who are depending on us to deliver food and provide medical care,” said Bangash

Presently, the Pakistani government is struggling to cope with the scale of the worst floods in the country's history. So far the flooding has killed at least 1,500 people, affected an estimated 15 million people, and added further strain to a country already dependent on foreign aid.

The United Nations on Sunday said Pakistan will need billions of dollars to recover from the flooding, which first hit two weeks ago after extremely heavy monsoon rains. And a spokesman for the World Food Program said at least four million people will need food assistance across Pakistan for the next three months at a cost of nearly $100 million.

"Khyber Pakhtunkhwa was a food insecure province even before the floods, and a lot of areas are such that people can't afford even one meal a day," WFP spokesman Amjad Jamal said, referring to the site of the worst damage from the floods.

“These floods bring even more devastation to poor, and disaster prone, areas of Pakistan,” added Joanne Fairley, Lutheran World Relief’s regional director for Asia and the Middle East.

According to LWR, the provinces of Khyber Pakhtunkhwa, Balochistan, Punjab and Sindh were most heavily affected by flooding. And the floods hit as people living in this region were still struggling to recover from five years of successive major disasters, with many families still living in makeshift shelters.

In 2005, a massive earthquake devastated parts of Pakistan. The two years following – 2006 and 2007 – brought floods that claimed lives, destroyed homes and killed livestock. In 2008, another powerful earthquake rendered thousands homeless in Balochistan at the onset of winter. And in 2009, millions were displaced as a result of conflict between the Pakistan military and militants in Khyber Pakhtunkhwa and Waziristan.

To compound matters, severe droughts and water shortages throughout those years severely plagued the country’s agricultural system and crippled its food supply.

With this new disaster, LWR says millions of Pakistanis are in danger of going hungry.

Despite the obstacles and difficulties, groups such as World Vision, LWR, and Catholic Relief Services are working quickly to deliver critical relief to people affected by this crisis.

"Our teams are battling the weather, the terrain and the immense scale of the disaster," reported Carolyn Fanelli, Head of Programming and Acting Country Representative for CRS Pakistan.

“World Vision is working hard to find creative ways around the barriers created by the flooding,” added World Vision’s Bangash, “but we are in a very difficult situation of needing to balance the safety of our staff against the needs of the millions affected by the floods.”

On Sunday, Pakistani Prime Minister Yousuf Raza Gilani asked for more help from the international community, saying the government couldn't cope with the disaster on its own.

"We will exhaust our resources to rescue, provide food, medicine and shelter, but it is beyond our capacity, so we will appeal to the world," said Gilani during a visit to Sukkur, according to The Associated Press.

Though the United Nations is still calculating specific figures, the U.N. special envoy for the disaster, Jean-Maurice Ripert, said in an interview with AP that the emergency phase will require hundreds of millions of dollars and the recovery and reconstruction part will require billions of dollars.

The United Nations said Monday that the number of people suffering from the massive floods in Pakistan exceeds 13 million - more than the combined total of the 2004 Indian Ocean tsunami, the 2005 Kashmir earthquake and the 2010 Haiti earthquake.